I don't know anything about this kit,however, it gives me pause.
Check out this
http://sites.google.com/site/undefinition/diy-sunflowersThese are open back in a "u" shape around top panel that is 4" wide. Lower woofer is enclosed. I am thinking about building a pair just to see how this open back speaker stuff sounds. I seen these speakers at the Dayton DIY event that runs in conjunction with the Parts Express July tent sale a couple of years ago and they sounded nice. Just my two cents but the info on these speakers makes for a nice read even if this design is not what you are looking for.
Robert